This Customer Support Ruling discusses
the use of the simplified address format for government
organizations that also qualify for Nonprofit Standard Mail rates.

Postal
regulations specify that official matter mailed by federal
government agencies; state, county, or municipal governments; or the
governments of the District of Columbia and the Commonwealth of
Puerto Rico may use the simplified address "Postal Customer" or "Boxholder"
when distribution is made to each stop or possible delivery on city
or village carrier routes, or to each post office boxholder at a
post office which has city or village carrier service. These
regulations were implemented at the behest of the Office of
Emergency Preparedness to provide government agencies with a speedy
means of communicating with citizens in emergencies.

Nonprofit
organizations as such, do not qualify under the postal regulations
for using the simplified form of address. However, some
governmental organizations, such as regularly established state
institutions of learning and public elementary or secondary schools,
normally are regarded as eligible to use the simplified form of
address. They also may qualify to mail at the Nonprofit Standard
Mail rates of postage.